This is a submission in response to PAR-14-052, Mechanisms of Behavior Change in the Treatment of Alcohol Use Disorders (R03), titled Meta-Regression to Identify the Impact of SBIRT Structure and Content on Outcome. Screening, brief intervention, and referral to treatment for risky alcohol use in primary care has shown strong efficacy and is recommended as part of routine clinical care. Despite this, fewer than 16% of Americans report having been asked about alcohol use by a healthcare provider. Little is known about the mechanism of behavior change in SBIRT and such information holds promise to improve the effectiveness of training and implementation efforts. There is significant unexplained heterogeneity in the results of SBIRT studies included in meta-analysis. Research reported includes limited details about the structure and content of SBIRT protocols. The purpose of this project is to develop an instrument to measure characteristics of SBIRT protocols that are not described in scientific reports and use meta-regression to determine their impact on outcome. The study sample will include 23 controlled trials from the 2012 Jonas meta-analyses on SBI in primary care. In addition, a website will be created that will serve as a repository for protocol descriptions and materials. The proposed project seeks to identify the mechanisms of behavior change underlying SBIRT using an innovative methodology that takes advantage of previous research investments.